Steel-concrete composite continuous beam bridge linear control method

Abstract

The application discloses a steel-concrete combined continuous beam bridge forming bridge linear control method, which comprises the following construction steps: S1. calculating the bending moment zero point of the continuous steel box beam and determining a plurality of position points for pre-segmentation in the bridge extension direction; S2. prefabricating a plurality of steel box beam bodies capable of being segmented at the position points set in S1; S3. after the erection of the side span permanent pier and the midspan permanent pier is completed, a plurality of temporary supports corresponding to the number of the position points set in S1 are erected at the position points, and pre-jacking is performed on the temporary supports; S4. assembling the plurality of steel box beam bodies to form the continuous steel box beam; S5. first unloading, so that the continuous steel box beam is unloaded from the pre-jacked state of the temporary supports to the state that the continuous steel box beam is in contact with the midspan permanent pier; S6. bridge deck concrete construction; S7. second unloading, so that the local self-weight bearing structure of the bridge is transferred from the temporary supports to the bridge structure, the forming bridge linear can be controlled, and the construction quality can be ensured.

Description

Technical Field

[0001] This invention relates to the field of bridge construction, and specifically to a method for controlling the alignment of a completed steel-concrete composite continuous beam bridge. Background Technology

[0002] With the national advocacy of low-carbon, green, and environmentally friendly development concepts, steel-concrete composite beams are gradually becoming more common in urban road and bridge construction. Steel-concrete composite beams offer significant advantages such as light weight, high load-bearing capacity, high stiffness, good seismic resistance, saving on formwork, fast construction speed, and good overall benefits. However, for highway bridges with large spans and road widths, or approach spans of cross-river bridges, the structural design often adopts a continuous multi-span, large-section steel box girder composite cross-section, commonly in the form of a fully bolted combination of "box girder + I-beam." Due to the differences in self-weight, stiffness, and moment of inertia between box girders and I-beams, inconsistencies in deflection speed and amount after installation can easily occur, affecting the bridge deck alignment. Therefore, determining the segment positions of large-span, ultra-wide steel-concrete composite continuous beam bridges, the erection of supports, the control of bolt drilling accuracy, and the selection of installation and unloading methods are crucial challenges that urgently need to be addressed to ensure construction quality and the final bridge alignment.

[0003] Therefore, a method for controlling the completed bridge alignment of steel-concrete composite continuous beam bridge is needed to solve the above problems. Summary of the Invention

[0004] In view of this, the purpose of this invention is to overcome the defects in the prior art and provide a method for controlling the bridge alignment of a steel-concrete composite continuous beam bridge, which can control the bridge alignment and ensure construction quality.

[0005] The method for controlling the completed bridge alignment of a steel-concrete composite continuous beam bridge according to the present invention includes the following construction steps:

[0006] S1. Calculate the zero bending moment point of the continuous steel box girder and determine several location points in the pre-segmented direction of the bridge extension;

[0007] S2. Prefabricate several segments of the main body of the steel box girder that can be segmented at the positions set in S1;

[0008] S3. After the permanent piers on the side spans and the permanent piers in the middle span are erected, a corresponding number of temporary supports are erected at the number of locations set in S1. Each location corresponds to one temporary support, and pre-lifting is performed on the temporary supports so that the steel box girder in the middle span does not come into contact with the permanent pier in the middle span during installation.

[0009] S4. Assemble several sections of the main steel box girder to form a continuous steel box girder;

[0010] S5. The first unloading process unloads the continuous steel box girder from the pre-lifted state of the temporary support to the state of contact between the continuous steel box girder and the permanent pier at the mid-span.

[0011] S6. Bridge deck concrete construction;

[0012] S7. The second unloading transfers the local self-weight bearing structure of the bridge from the temporary support to the bridge's own structure, completing the transformation of the load-bearing system from a continuous beam to a simply supported beam to a continuous beam during bridge construction.

[0013] Furthermore, both the first and second uninstallations follow the principle of proceeding symmetrically and synchronously from the middle outwards.

[0014] Furthermore, the continuous steel box girder is a statically determinate continuous beam with three spans.

[0015] Furthermore, when calculating the zero bending moment of the continuous steel box girder, a bending moment diagram is drawn, and a temporary support is arranged at each zero bending moment point to transform the three-span continuous beam into a five-span simply supported beam.

[0016] Furthermore, in step S2, after prefabricating several sections of the steel box girder body that can be segmented at the positions set in S1, the prefabricated sections of the steel box girder body are assembled and inspected; the inspection items include at least the bolt perforation rate, bridge camber, and the transverse and longitudinal slopes of the bridge deck.

[0017] The beneficial effects of this invention are as follows: The method for controlling the bridge alignment of a steel-concrete composite continuous beam bridge disclosed in this invention involves setting up temporary supports at the zero-moment position of the steel box girder as temporary hinge supports for the simply supported beam before installation. Pre-lifting is then performed on the temporary supports, which is equivalent to applying a reverse force to adjust the stress and bridge alignment of the steel box girder, making the alignment closer to the design value and improving installation accuracy. During the pouring of the bridge deck concrete, although the load increases, the permanent piers and temporary supports are simultaneously loaded. Compared to the traditional construction process of pouring concrete on temporary supports and then unloading it uniformly, this method effectively reduces the design cross-section of the temporary supports. Therefore, lightweight supports can meet the load requirements throughout the entire construction process. The two unloading operations follow the principle of symmetrical unloading from the middle to both sides. First, temporary supports #2 and #3 are unloaded synchronously, followed by supports #1 and #4. Synchronous unloading is controlled by a jack array, ensuring that each support point on the supports is unloaded synchronously at symmetrical locations, thus preventing large unloading internal forces in the bridge structure and ensuring structural safety. Attached Figure Description

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0019] Figure 1 This is a schematic diagram illustrating the process principle of the present invention;

[0020] Figure 2 This is a schematic diagram of the zero bending moment point for a continuous steel box girder.

[0021] Figure 3This is a schematic diagram of the overall pre-assembly of the steel box girder;

[0022] Figure 4 Schematic diagram of temporary support structure. Detailed Implementation

[0023] Figure 1 This is a schematic diagram of the structure of the present invention, as shown below. Figures 1-4 As shown: The method for controlling the bridge alignment of the steel-concrete composite continuous beam bridge 2 in this embodiment includes the following construction steps:

[0024] S1. Calculate the zero-moment point of the continuous steel box girder 1 and determine several pre-segmented locations along the bridge's extension direction; accurately calculate the zero-moment point of the continuous steel box girder 1 as the longitudinal segmentation location; the original state of the steel box girder is a statically determinate continuous beam with three spans, such as... Figure 2 As shown, the bending moment diagram is drawn, with points B, D, E, and G being the zero bending moment locations. The zero bending moment locations are the longitudinal segmentation points of the continuous steel box girder 1. Calculations have shown that this segmentation method meets the requirements for component fabrication, transportation, and hoisting, and prefabrication work can then proceed.

[0025] S2. Prefabricate several sections of the main body of the steel box girder that can be segmented at the positions set in S1; manufacture in sections in the factory and pre-assemble as a whole; customize the continuous steel box girder 1 in the factory in a segmented manner, separately manufacture the box girder 11, the I-beam longitudinal beam and the main and secondary cross beams, and then pre-assemble the whole of a single span; when pre-assembling the whole of a single span, ensure the bolt perforation rate, bridge camber and bridge deck transverse and longitudinal slope, thereby improving the assembly quality.

[0026] S3. After the permanent piers 3 on the side spans and the permanent pier 4 in the middle span are erected, a corresponding number of temporary supports 5 are erected at the locations specified in S1. Each location corresponds to one temporary support 5, and pre-lifting is performed on the temporary supports 5 to ensure that the steel box girder in the middle span does not contact the permanent pier 4 during installation. The temporary supports 5 are prefabricated standard segmental supports, and the number of segments of the temporary supports 5 is designed according to the installation height of the bridge. Temporary supports 5 are set at the zero-moment locations to transform the three-span continuous beam into a five-span simply supported beam. The stress points of the continuous beam cause changes in its beam system, which is beneficial for controlling the bridge alignment. During on-site installation, the bottom of the support is first pre-embedded and hardened. The support foundation is made of 600mm thick C25 concrete to meet the bearing capacity requirements of the foundation at the bottom of the support. The bottom segments of the support are connected to the foundation through pre-embedded parts, and the segments are connected by flange joints. The main body of the support is erected according to the design number of segments. The supports are connected laterally with I-beams to form a whole. The lower part is connected laterally, and the uppermost segment is designed as a lattice structure to enhance the lateral resistance.

[0027] S4. Assemble several sections of steel box girder to form a continuous steel box girder 1; during the installation of the steel box girder, install each section of the steel box girder in sequence according to the installation order of the steel box girder. After the high-strength bolts of each section of the component are connected into a whole, the cover plates between the main and secondary crossbeams and the shear keys on the crossbeams are then installed and welded in place; thereby further controlling the bridge alignment of the continuous beam; and meeting the preset alignment requirements.

[0028] S5. The first unloading is to unload the continuous steel box girder 1 from the pre-lifted state of the temporary support 5 to the state of contact between the continuous steel box girder 1 and the permanent pier 4 in the middle of the span; after the steel box girder is installed, the first stage of unloading is carried out; before unloading, the support piers at the bottom of the I-beam 12 are removed, and only the support piers corresponding to the web of the box girder 11 are retained. The box girder 11 is lifted and the support piers are lowered to allow it to actively deflect downwards. The I-beam 12 follows the box girder 11 and is passively deflected downwards, thereby ensuring consistent deflection; the first unloading is to unload the continuous steel box girder 1 from the pre-lifted state of the temporary support 5 to the state of contact with the permanent pier 4 in the middle of the span.

[0029] First, the temporary supports 2 and 3 are unloaded synchronously, then the supports 1 and 4 are unloaded synchronously, and finally a balanced state is formed in which the permanent pier and the temporary supports 5 are loaded at the same time. The synchronous unloading is controlled by the jack array through the same main control box, so that the unloading of each support point on the support at the symmetrical position is completed synchronously at each step.

[0030] The unloading process adopts a multi-step equidistant unloading method, with each step unloading height being 10mm. Auxiliary piers and 10mm pads are required for assistance during the unloading process to improve the reliability of the continuous beam bridge alignment control.

[0031] S6. Bridge deck concrete construction; After the steel box girder is installed and unloaded to form an overall stable structure, bridge deck concrete construction is carried out; Before pouring bridge deck concrete, steel bars are laid between the shear keys with openings, side formwork is supported at the beginning and end of the single steel box girder, and then bridge deck concrete is poured.

[0032] S7. The second unloading transfers the local self-weight load-bearing structure of the bridge from temporary support 5 to the bridge's own structure, completing the transformation of the load-bearing system from a continuous beam to a simply supported beam to a continuous beam during bridge construction. The second unloading is carried out after the bridge deck concrete strength reaches the design requirements. The second unloading also follows the principle of symmetrical unloading from the middle to both sides. First, temporary supports #2 and #3 of #5 are unloaded simultaneously, then supports #1 and #4 are unloaded, gradually transferring the local self-weight load-bearing structure of the bridge from temporary supports 5 to the bridge's own structure.

[0033] In this embodiment, both the first and second unloading follow the principle of symmetrical and synchronous operation from the middle to both sides, which is beneficial for controlling the bridge alignment of the continuous beam.

[0034] In this embodiment, the continuous steel box girder 1 is a statically determinate continuous beam with three spans.

[0035] In this embodiment, when calculating the zero bending moment of the continuous steel box girder 1, a bending moment diagram is drawn, and a temporary support 5 is arranged at each zero bending moment point so that the three-span continuous beam is transformed into a five-span simply supported beam.

[0036] In this embodiment, in step S2, after prefabricating several sections of the main body of the steel box girder that can be segmented at the positions set in S1, the prefabricated sections of the main body of the steel box girder are assembled and inspected; the inspection items include at least the bolt perforation rate, bridge camber and the transverse and longitudinal slope of the bridge deck.

[0037] In this scheme, before the steel box girder is installed, a temporary support 5 is set at the zero-moment position as a temporary hinge support for the simply supported beam. Pre-lifting is carried out on the temporary support 5. Pre-lifting is equivalent to applying a reverse force to adjust the stress of the steel box girder and the bridge alignment, making the alignment closer to the design value and improving the installation accuracy. When the bridge deck concrete is poured, although the load is increased, the permanent pier and the temporary support 5 are loaded at the same time. Compared with the traditional construction process of pouring concrete on the temporary support 5 and then unloading it at the same time, the design section of the temporary support 5 can be effectively reduced. Therefore, the load requirements can be met by using a lightweight support throughout the construction process. The two unloadings follow the principle of symmetrical unloading from the middle to both sides. First, the temporary supports 5 of No. 2 and No. 3 are unloaded synchronously, and then the supports 1 and No. 4 are unloaded synchronously. Synchronous unloading is controlled by a jack array, so that the unloading of each support point on the support at the symmetrical position is completed synchronously at each step, so as to ensure that the bridge structure does not have large unloading internal forces and ensure structural safety.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for controlling the completed bridge alignment of a steel-concrete composite continuous beam bridge, characterized in that: The construction steps include the following: S1. Calculate the zero bending moment point of the continuous steel box girder and determine several location points in the pre-segmented direction of the bridge extension; S2. Prefabricate several segments of the main body of the steel box girder that can be segmented at the positions set in S1; S3. After the permanent piers on the side spans and the permanent piers in the middle span are erected, a corresponding number of temporary supports are erected at the number of locations set in S1. Each location corresponds to one temporary support, and pre-lifting is performed on the temporary supports so that the steel box girder in the middle span does not come into contact with the permanent pier in the middle span during installation. S4. Assemble several sections of the main steel box girder to form a continuous steel box girder; S5. The first unloading is to unload the continuous steel box girder from the pre-lifting state of the temporary support to the state of contact between the continuous steel box girder and the permanent pier in the middle of the span. Before the first unloading, the support piers at the bottom of the I-beam are removed, leaving only the support piers corresponding to the web of the box girder. The box girder is lifted and the support piers are lowered to make it actively deflect downwards. The I-beam follows the box girder and deflects passively to ensure consistent deflection. S6. Bridge deck concrete construction; S7. The second unloading transfers the local self-weight bearing structure of the bridge from the temporary support to the bridge's own structure, completing the transformation of the load-bearing system from continuous beam to simply supported beam to continuous beam during the bridge construction process; Both the first and second uninstallations follow the principle of symmetrical and synchronous execution from the middle outwards. Synchronous unloading is achieved by uniformly controlling the jack array through the same main control box, with each unloading step having a height of 10mm. The continuous steel box girder is a statically determinate continuous beam with three spans. When calculating the zero bending moment of the continuous steel box girder, a bending moment diagram is drawn, and a temporary support is arranged at each zero bending moment point to transform the three-span continuous beam into a five-span simply supported beam.

2. The method for controlling the bridge alignment of a steel-concrete composite continuous beam bridge according to claim 1, characterized in that: In step S2, after prefabricating several sections of the steel box girder body that can be segmented at the positions set in S1, the prefabricated sections of the steel box girder body are assembled and inspected; the inspection items include at least the bolt perforation rate, bridge camber, and transverse and longitudinal slope of the bridge deck.

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